tjwalker

Primary operating temp above 60 degrees F: 10-30

Primary operating temp below 60 degrees F: 5-30

djb383

.....but they're are both 30 at normal operating temp and 5W30 will flow quicker/better than 10W30 when below normal operating temp regardless of the ambient temp.

RaiderMike67

I'd just follow the manufacturers recommendation.

peep

Well there is a lot of data available on the subject.
Here is my Cherokee science experiment. Original owner kept records, changed oil and filter every 5 to 6000 km.
I change every 5 to 7000km, new fram filter every time (about every 5 to 6 weeks for me). I use 10W30, sometimes I use the hi mileage if it is on sale. I use a name brand, not the bargain brand. The Peep has over 493000 km, I use up to 800 ml added between the oil changes if I have been doin a lot of 70mph hiway running, else I use 300 to 500 ml between changes. The Peep has leaks (yes all the gaskets, seals, o rings have been changed at least once, time for more oil leak repairs in the spring, I am sure I must burn some but no smoke clouds from exhaust and plugs run clean). So my theorum is regular oil and filter changes, my results data is hi miles and still goin.

2Evil4U

There is a spectacular amount of silliness in this thread. (And every other bloody lubrication thread on this and about all other sites, with the possible exception of the NORIA website.)

Here, (again) is a graph showing the temperature/viscosity lines for various straight weight oils compared to a 10W30.



Multi weight oils change the slope of the viscosity curve. They certainly don't act like one weight cold and a different wieght hot. If you look closely you'll notice that the 10W30 curve never even gets close to as thick as a 30W. At -20F it is lower viscosity than 10W and at 212F it has a higher viscosity than 20W, but a lower viscosity than 30W.

A 5W30 viscosity line should be about parallel to the 10W30 line, but lower across the board.

Look at the graph and, if you can comprehend it, make your own decisions about what oil to use.

Your 4.0L should have 10W30 in it assuming it is in good running condition. (unless you are consistently operating in very cold temps.)

Ruffnek

Point taken, but why do all old 4.0s make lifter noise then? I swapped my cam, lifters and valve springs with a high lift Comp Cam, and use a ZDPP oil and no more valvetrain noise whatsoever. 10w30 BTW. So to comment on the original thread, you don't need a heavier oil due to the flat tappet cam, but one that contains ZDPP, if you want to avoid the same lifter tick that these engines all seem to develop.
Shell Rotella T contains ZDPP and it is also available as an additive and in some other specialty oils as well.
My 4.0 has 275k km on it and I will attest that it does start easier and idle smoother below freezing with a 0W30 than 10W30. But I live in Canada and mornings are below freezing for 6 months of the year here.

my 2cents

gthbryce

Well I ended up using 5w 40 shell synthetic t6. Only because I have a oil pan leak and did not want to start off with a lower viscosity and just wanted to see if the lifters quieted down. I plan to go 10w 30 next oil change, or should I bother?

Spoonman

5w-30 is lighter than 10w-30.If you want to quiet the lifters then you would need to try the 10w-30. Either way I would not use anything other than one of the two that I mentioned.Defiantly do not go any lower than 0w-40 in fact I don't recommend 0w oils be used at all as they are mainly used for flushing gunk from the engine or extremely cold climates .Besides that if you have a tap at operating temp then the 0w is going in the wrong direction.
I would just go with a 10w-30 next oil change

SamSissine2

I would stay with 5w-40 before I would go with 10w-30.. Now, with that being said, if you want to go lighter then I would consider a 5w-30.. In Cali. you need more flow not higher viscosity. Higher flow means better cooling. The difference between xW-40 and xW-30 is really minimal so stay with what you feel comfortable with but don't put your internals in jeopardy, keep that initial number as low as possible. A high quality oil is going to provide the anti-wear additives that your engine needs for protection.

SamSissine2

**First off I can not see your picture, I am assuming its because of how it was added(not as a attachment)**

Now, I don't see where the silliness is?? No one is throwing out crap just resources?? Seems to me like that should be condoned as beneficial to any uninformed.

I dont know where your graph is from but here is one that you or anyone can find by opening the #2 link(Widman) above. There is actually a lot of great graphs if you look at that pdf.. Probably one of the most in-depth oil break downs and it is specific to flat tappet.... but hey that just silliness, right??

This will show that the correlation from a 10w-30 and straight 30 are pretty close if not exact @ operating temp., maybe I misunderstood your previous post but it seemed like you were saying this was not the case.

djb383

At what temp is 5W30 lighter than 10W30? At what temp does more wear occur? At what temp are they the same weight?

I believe there are a number of autos filled at the factory with 0WXX or 5WXX.....not many new engines need a flush. Since all 0WXX motor oils are synthetic, what manufacturer would NOT want you run synthetic in their/your engine?

2Evil4U

Beats me. It's an image file from photobucket. Been posting them the same way for 12 years. Here's the direct link.

http://img.photobucket.com/albums/v1...lviscosity.jpg

This line of misunderstanding that is never properly explained is what I was referring to. 5W30 will always be lighter at all temperatures than 10W30. They are never the same viscosity. (Within reason. There is probably some ludicrously high and low temps where the individual viscosities are within a certain margin of error.) Multiweight oils do not magically transform from "5W" to "30W" at some engineered temperature. They oils merely have different slopes to their respective viscosity curves.


Edit: I just power read the Corvair PDF. He's basically correct, although, having read most, if not all of the API docs he plagiarized, I don't agree with some of his summarizations. Even the page reprinted above. His second to last bullet point for example, is correct, but barely agrees with the chart that shows that SAE 30 and 10w30 are almost identical. The last bullet is true of all oils, not just multi-grade. It also seems obvious, if the branded comparisons are correct, that discussions of viscosity between brands are worthless.

SamSissine2

At work, it blocks me from seeing any images that are added through a URL and not posted as a attachment. (not big deal or anything you are doing wrong)


Did you see the above graph that I posted from a reliable source, it shows what you are stating as false?? The operating temp visco on a 5w-30, 10w-30 or any sae 30 weight oil will be the same they will continue to differ as temp continues to increase but @ 100c(roughly) they will be the same hence the 30 weight designation on them all.

gthbryce

And this is why I was so confused at what weight to choose although I got to the point I did not care because my oil was BLACK. Everyone on every forum stresses their own knowledge based opinion along with links and graphs and such. I will re-read everyone's input here and base my long-term oil choice on that. My first vehicle and first Forums were the Ford Truck Enthusiasts Forums and I drove a 1989 Ford F-250 XLt Lariat with a 460. Everyone their was helpful, nice and very informative, it appears you all have a relatively high degree of knowledge and know how and so far my experience here is great. Thanks for all the help with my first thread post!

SamSissine2

Welcome to the boards!

Oil is a pretty vast topic, I love to talk about it because there is so many opinions. I may be alone in that love though, many others on here hate the oil threads.

The reason I think you were feeling confused is everyones scenario is very specific so for me my ideal weight is 5w-20 or 0w-30, but as a recommendation to you??? Your driving may be a ton different and I know your weather is, im in NC..

Hope you gather some good info from looking through the covered info. You picked a great oil no matter where you are and if you change it often enough all these discussions may not matter to much..